0-1.2m below the turf is just topsoil, man made, this layer soaks up drainage from the site. Beneath the layer of topsoil is 3m of sand and gravel, composed mainly of fine particles of flintstone, chalk and limestone. A 2m layer of clay lies below this, which is fairly soft so pile foundations would be required to pierce into the calcareous mudstone (the supporting ground). The borehole data stopped at -20m, but I presume the mudstone layer continued below this.
The most interesting we discovered was the large amount of fossils that have been found in Cambridge, in the layer of mudstone. These are all marine fossils, indicating that Cambridge and The Fens region of Eastern England was at one time in history (we think the cretaceous era) submerged under water.
We researched the feasibility of construction on site, which with such a large site was quite straightforward. Construction vehicles have good links to the site from Grange Road, less than 2 miles from the motorway.
The diagram below is to scale, and shows:
Red rectangle indicates size of maximum (single) portacabin.
Blue rectangle indicates maximum size of lorry on UK road.
Orange circle shows maximum turning circle for the lorry (vehicle must be able to drive inside the orange doughnut shape).
Green shape is the access/servicing road to the University Library, and must not be obstructed in construction.
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